Monday, July 16, 2007

Incurable bone chewers

That moose antler was a gift from my older daughter. It was already weathered and chewed by a porcupine when a grad student found it in northern Minnesota. My daughter bugged the grad student until he gave it to her, and then she shipped it to me in Virginia. It arrived in a very large box. A gift for a goofy dad. Yes, biologists are a little weird.

I made this cool sign out of it, and I liked it a lot, so when we moved to California I hauled it along.

It's a bone of contention. Every now and then the redhead discovers some useless but sentimental thing that I saved from the past (like the antler), and gently reminds me that she jettisoned all kinds of useful things when we packed off to California.

My daughters and I respond to these observations the same way.

"You married me (him). You knew what I (he) was like. I (he) can't help it. Biologists are a little weird."

Her point of course is well taken, a gentle reminder of the tolerance and sacrifices of a biologist's spouse.

Well, back to the story. It didn't take long for the squirrels to discover my eponymous moose antler, and we developed a routine. I hear the unmistakable sound of rodent gnawing antler, stop what I am doing, sneak around the garage, and suddenly but quietly make my appearance.

The squirrel stops gnawing, but doesn't flee.

"What in the hell do you think you're doing?!"

It hesitates and looks at me bug-eyed, and then discretely makes off into the canopy.

It's all false bravado, of course. I actually don't mind them eating the antler.

The fact of the matter is that rodents are incurable bone chewers, and antlers are just bones, though very special ones. Hardly anything, except metastatic cancer grows as fast as deer antlers in velvet. When the growth is complete the cartilage is thoroughly embedded with calcium, phosphorus and various trace elements, and as the velvet peels the buck, stag or bull undergoes a personality change. It's a hormonal thing. Testosterone, the evil hormone that confuses rational thought transforms relatively docile velvet-antlered male deer into aggressive, anorexic, sex-crazed hard-antlered fiends.

In due course, the deer that survive the hunt shed their proud adornments and their sex-vanity, and the antlers lie there in the snow or on the damp duff.

Then come the "antler collectors" and the antler eaters. Antlers are worth money these days, and a lot of antler or shed collectors are good capitalists. They want to beat the competition. They also know that if they wait too long, the rodents will start to eat the antlers, and diminish their value. So they like to start looking early, and this can be a problem. When people are wandering around the woods in the dead of winter and deer are living on hard times it can put the deer at a disadvantage.

On the other hand, the shed eaters -- mainly rodents and rabbits are just responding to their physiological needs. They're capitalizing on a concentrated source of calcium and other minerals found in bone. Only a small percentage of the calcium in the mammalian skeleton is dissolvable and can be accessed for fetal growth, lactation, and the unending growth of the incisor teeth. So external sources of calcium are important. Calcium is an abundant element, but it's a lot easier for a rodent to gnaw a bone that chew limestone.

My casual observations of bone-gnawing squirrels suggest that it occurs year round. Consider this a hypothesis. I assume that the demand for calcium for the ever-growing incisor teeth is more or less constant, and assume that bone-gnawing is also a continuous habit. Who's going to do the experiment? Or who's going to direct me to the published results? So many questions!

Meanwhile, this old fool watches his moose antler slowly shrink, and verbally abuses the squirrels who come and go and help themselves. Yes, biologists are a little weird, but we're harmless, sometimes lovable, and we sure know how to have fun.

I'm finding myself enjoying your posts more and more. And well done on this one: I lecture on hoofed mammal evolution, and I just love telling people how freakin' bizarre deer are. I mean: they grow bones out of their tops of their heads.. shed them.. and eat them (very few people seem to know about the eating bit). If people are collecting antlers with gay abandon nowadays, is this causing the deer any problems? You've probably heard of cases where calcium-deprived deer resort to bizarre behaviour like biting the heads and feet off nestling birds.

As for rodents and their quest for calcium, I agree that the need is probably year-round. They probably get through an awful lot of bones, and also snail shells.

Well Darren, I guess I need to slow down a bit and keep reading the comments to past posts. I agree 100% about how strange deer are carrying ornate boney adornments on their heads, and have been an admirer of Irish elk for many years now, but I'm afraid I don't have any trees big enough to hang one of their antlers. LOL